The styrene resins comprise a family of thermoplastic polymers known to be injection moldable into various shaped articles. These resins are normally highly flammable, however. As a way of decreasing the flammability, it has been proposed to incorporate halogen substituents, such as chlorine or bromine groups, into the polymer structure. For instance, British patent No. 986,634 discloses the preparation of chloro- and bromo-benzenes which are said to be useful in the production of self-extinguishing polymers and copolymers.
DeMan, et al. in U.S. Pat. No. 4,412,051 describe fire-resistant copolymers of bromostyrene and one or more other monomers, including acrylonitrile, alpha-methylstyrene and maleic anhydride. Methods of preparation are said to include bulk, solution, suspension, emulsion and precipitation. The preferred mode involves the addition of bromostyrene to an aqueous emulsion of acrylonitrile monomers, in which are also included an emulsifying agent and a free radical initiating compound.
It is known from Cizek, U.S. Pat. No. 3,383,435 and elsewhere in the patent literature that styrene resins can be utilized together with polyphenylene ether (oxide) resins in the form of molding compositions which exhibit beneficial properties as a result of the conjoint use. Compositions of a polyphenylene ether resin and a styrene resin in which the styrene resin can be modified to contain chloro or bromo substituents have also been described in Cooper, et al., U.S. Pat. No. 4,101,503, and in Yonemitsu, et al., U.S. Pat. Nos. 3,887,646 and 3,887,647.
Canadian Pat. No. 1,149,984 discloses a flame retardant polymer based on styrene, halogenated styrene, acrylonitrile and butadiene.
U.K. published application No. 2 076 831 describes molding compositions of a polyphenylene ether resin and a styrene-bromostyrene copolymer.
European published patent application No. 0 013 052 discloses fire-resistant copolymers of bromostyrene and a comonomer, preferably acrylonitrile.